Many semiconductors such as IC, transistors, LSI, etc., are sealed using epoxy resin compositions.
Epoxy resin compositions comprise an epoxy resin as the principal component, a curing agent for the epoxy resin, a curing accelerator, an inorganic filler, a flame retarder, a pigment and a silane coupling agent. The epoxy resin compositions must have various characteristics such as flame retardance, reliability in terms of moisture resistance to water penetrating from the outside, high adhesion, crack resistance and electrical characteristics (e.g., high volume resistivity, etc.).
With the high level of integration of semiconductors which has occurred recently, the width of aluminum wiring on IC chips has been reduced and corrosion of aluminum has occurred prematurely. Corrosion is promoted by the presence of water which penetrates into the epoxy resin compositions. Accordingly, epoxy resin compositions must provide further improvement in the corrosion-resistance for aluminum wiring, etc., and must improve the reliability of aluminum wiring, etc., to moisture resistance (hereinafter generally called reliability on moisture resistance or moisture resistance reliability).
Further, since the heat generated is increased due to a reduction in the width of the wiring, a large amount of a flame retarder, such as antimony oxide or an inorganic hydroxide, is blended with the epoxy resin composition. However, the corrosion of aluminum wiring is further accelerated by the flame retarder component. This problem must be solved.
To solve this problem, use of antimony-bismuth or bismuth nitrate oxyhydroxides represented by the following formulae has been proposed (see, U.S. Pat. No. 4,716,184 and JP-A-63-60112 (the term "JP-A" as used herein means an "unexamined published Japanese patent application")): EQU SbBi.sub.x O.sub.y (OH).sub.z (NO.sub.3).sub.w .multidot.nH.sub.2 O
wherein x represents 0.2 to 2.0, y represents 1.0 to 5.0, z represents 0.1 to 3.0, w represents 0.1 to 3.0 and n represents 0.5 to 3.0; and EQU Bi.sub.6 O.sub.6 (OH).sub.x,(NO.sub.3).sub.6-x,.multidot.n'H.sub.2 O
wherein 3.5.ltoreq.x'.ltoreq.5.5 and n' represents 0 or a positive number.
Epoxy resin compositions for sealing semiconductors, which contain the above described bismuth compound prevent sealed wiring, etc., from corroding and have high reliability for moisture resistance.
When the above bismuth compound is blended with epoxy resin compositions, moisture resistance reliability can be improved. However, there are disadvantages with this approach in that electrical characteristics are deteriorated, the volume resistivity of resin compositions is reduced in comparison with resin compositions which do not include the bismuth compound, and the electric conductivity of hot water-extracted water is increased.